Apolipoprotein B, apolipoprotein E, and angiotensin-converting enzyme polymorphisms in 2 Italian populations at different risk for coronary artery disease and comparison of allele frequencies among European populations

Polymorphisms at the apolipoprotein B (APOB XbaI, EcoRI, insertion-deletion ), apolipoprotein E (APOE), and angiotensin-converting enzyme (ACE) loci ar e thought to be involved in susceptibility to coronary artery disease (CAD) and myocardial infarction. The aim of this study was to determine whether the allele distribution of the APOB, APOE, and ACE polymorphisms is differe nt in 2 Italian regions with higher (northern Italy) and lower (Sardinia) C AD occurrence. The frequencies of the APOB and APOE alleles that are consid ered CAD risk factors were higher in northern Italy (APOB X- = 0.655; APOB R- = 0.198; APOB insertion = 0.757; APOE*4 = 0.110) than in Sardinia (APOB X- = 0.568; APOB R- = 0.159; APOB insertion = 0.680; APOE*4 = 0.052), altho ugh only APOE allele frequencies differed significantly (p = 0.001). ACE de letion allele frequencies in the 2 geographic areas showed an opposite patt ern (northern Italy = 0.658; Sardinia = 0.721). Furthermore, we investigate d the impact of APOB and APOE polymorphisms on interindividual variation in total cholesterol level in the 2 Italian samples, which differ in dietary habits. Only APOE phenotypes showed different mean levels of total choleste rol; the association was significant only in northern Italy (p = 0.04), whe re continental dietary habits and higher mean cholesterol levels prevail. T hese results support the suggestion that the cholesterol increasing effect of APOE*4 is environmentally mediated. Analysis of allele distributions amo ng European populations, with remarkable differences in CAD prevalence, rev ealed a constant positive relationship between APOE*4 allele frequency and CAD incidence. The highest frequencies of APOB X- and R- were observed in F inland, where the incidence of CAD is high, and there is a partial agreemen t between APOB R- frequency and CAD occurrence across Europe, while APOB in sertion and ACE deletion alleles are evenly distributed among European popu lations.